Product Review: JD Jetting Kit Is Ultimate Fix For Yamaha WR 250f
Let’s face it, not everyone needs a full blown works racing bike to satisfy being a weekend warrior rider. A fun, reliable, low maintenance dirt bike can produce endless smiles along countless trails. The Yamaha WR 250f meets the challenge. It’s a great all-around enduro bike, with proven Yamaha reliability. The handling and suspension are excellent, and the maintenance is simple and low cost. The problem however, is that Yamaha’s WR 250f comes out of the crate with way too many “political corks” and restrictions cast upon it. Yamaha successfully created a phenomenal off-road dirt bike for the masses, and then choked it badly…so badly that it simply cannot breath properly. Once uncorked, the WR 250f’s performance is vastly improved and worlds apart from it’s original factory state.
We set out to ‘uncork’ our WR 250f in order to allow the bike to perform better. The bike has serious bogging issues in stock form, and the power is robbed by restrictions installed at the factory. Once we completed our list of modifications, the bike ran much better. All of the tasks were fairly simple to do, and best of all they were all mostly free. We still couldn’t get the jetting perfectly spot on though. We tried many different jets and settings, and found none of them to work perfectly. Our WR 250f was relieved to be ‘uncorked’ and wanted to be ‘unleashed’ into the wild…but the Keihn FCR 37mm carburetor just wouldn’t cooperate. So, for expert jetting advice, we turned to the indisputable FCR experts at James Dean Jetting (JD Jetting).
JD jetting is the industry leader, known for producing highly accurate and effective dirt bike jetting kits. The company was founded long before most of today’s motocross stars were even born. JD Jetting is the motocross community’s number one source for expert advice regarding Keihin and Mikuni carburetor jetting concerns. JD’s jetting kits are not only thoroughly tested using dyno technology, but each kit comes with the exact specifications for your bike and settings for your track location’s altitude. The JD Jetting kit was exactly what we needed to complete the job of restoring power to our Yamaha WR 250f. JD sent us a JDY011 kit … specific to the WR 250f’s Keihin 37mm carburetor. At just under $80, the kit was worth it’s weight in gold considering the improved performance. It was absolutely astonishing how well the kit worked on the WR 250f, especially when compared to results of our own stubborn tinkering of the jetting. JD’s proprietary needle may possibly be what solved the bike’s ‘hick-ups’. Other hardware in the kit seemed standard, but their specialized ‘red’ needle, specific to our bike’s carburetor, was a proprietary JD product and certainly made the Yamaha sing … especially when combined with our other modifications. The instructions helped us to fine tune the leak jet, main jet, needle and needle clip to our location’s altitude (sea level to 3000ft elevation). The kit also included a perfectly sized o-ring to wrap around the accelerator pump linkage screw in order to help prevent excessive bogging. We also installed a JD jetting fuel screw as advised by JD in order to accurately fine tune the carburetor’s air/ fuel mixture.
The kit itself was simple to install. The biggest challenge was getting clear access to the Yamaha’s large Keihin 37mm carburetor. The aluminum frame’s design was so erognomic, that it became necessary for us to remove the gas tank, seat, and subframe, in order to have enough access to complete the kit installation. Certainly carburetors on today’s modern bikes are not as easy to access, as they were on classic vintage iron bike’s from the past! Overall, the JD jetting kit did the trick and was the real missing link to perfectly dialing in our weekend warrior WR 250f. Cheers, Chronic MX.
Inexpensive modifications done to ‘uncork’ the Yamaha WR 250f:
1. Cut Gray Wire (behind rear left number plate)
2. Removed snorkel contraption from the air box
3. Drilled several vent holes in the top of the WR’s air box
4. Removed pea shooter from exhaust baffle.
5. Blocked off 3 tubes in the AIS system using AIS removal kit
6. Flipped the ACV valve
7. Cut 8mm off of the throttle stop screw.
8. Installed JD Jetting JDY011 Kit (60 Leak Jet, Red JD needle with clip in #3 psoition, 180 Main Jet).
9. Installed JD Jetting Fuel screw (2 turns out)
10. Add o-ring around the accelerator pump linkage (o-ring included in JD kit)